I downloaded the manual and studied the display circuit. Its a
multiplexed display where the driver puts out the bits for each number
in sequence and a digit select line enables the appropriate chip. To get
an extra digit means the digit select sequence has to have an extra bit
part of the time, its a glitch so flickering and low intensity might be
part of the problem. The link from the control board to the display
driver board is a serial data link. I think I'd attack board grounding,
connections, and electrolytic capacitors, replacing all the capacitors
on the control, display driver, and display boards with high temperature
very low ESR caps. I might try some heating and cooling to see if I
could find a spot that cycling would make the extra digit come and go.
Careful inspection of the soldering might turn up some intermittents
too, but alternating hot and cold should make those show up.
73, Jerry, K0CQ
On 9/15/2010 8:46 AM, John Molenda wrote:
That extra number flickers and looks to be only half as bright as the
others . Now I just turned the radio on for a 45 min and the display is
fine . John
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